用 GDI 操作 EMF 文件[8]: 绘制图元文件时改变画笔与画刷

本例效果图:

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代码文件:

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unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls, ExtCtrls;



type

  TForm1 = class(TForm)

    ColorBox1: TColorBox;

    ColorBox2: TColorBox;

    ComboBox1: TComboBox;

    procedure FormCreate(Sender: TObject);

    procedure FormDestroy(Sender: TObject);

    procedure FormPaint(Sender: TObject);

    procedure ColorBox1Change(Sender: TObject);

    procedure ColorBox2Change(Sender: TObject);

    procedure ComboBox1Change(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



var

  HMetaFile: HENHMETAFILE; {EMF 文件句柄}

  p: TPen;

  b: TBrush;



//EnumEnhMetaFile 的回调函数

function MyEnhMetaFunc(DisplaySurface: HDC; var MetafileTable: THandleTable;

  var MetafileRecord: TEnhMetaRecord; ObjectCount: Integer; var Data: Longint

  ): Integer; stdcall;

begin

  case MetafileRecord.iType of

    EMR_CREATEPEN: SelectObject(DisplaySurface, p.Handle);

    EMR_CREATEBRUSHINDIRECT: SelectObject(DisplaySurface, b.Handle);

  else

    PlayEnhMetaFileRecord(DisplaySurface, MetafileTable, MetafileRecord, ObjectCount);

    Result := 1;  

  end;

end;



procedure TForm1.FormCreate(Sender: TObject);

var

  MetaFileDC: HDC;

begin

  {文件建立在内存}

  MetaFileDC := CreateEnhMetaFile(0, nil, nil, nil);

  p := TPen.Create;

  b := TBrush.Create;

  p.Color := clRed;

  b.Style := bsCross;

  b.Color := clSilver;



  SelectObject(MetaFileDC, p.Handle);

  SelectObject(MetaFileDC, b.Handle);



  MoveToEx(MetaFileDC, 0, 0, nil);

  LineTo(MetaFileDC, 80, 80);

  {矩形}

  Rectangle(MetaFileDC, 10, 10, 30, 50);

  {椭圆}

  Ellipse(MetaFileDC, 30, 30, 50, 70);



  HMetaFile := CloseEnhMetaFile(MetaFileDC);



  DeleteObject(MetaFileDC);



  ComboBox1.Items.CommaText :=

    'bsSolid,bsClear,bsHorizontal,bsVertical,bsFDiagonal,bsBDiagonal,bsCross,bsDiagCross';

end;



procedure TForm1.FormPaint(Sender: TObject);

begin

  EnumEnhMetaFile(Canvas.Handle, HMetaFile, @MyEnhMetaFunc, nil, ClientRect);

end;



procedure TForm1.ColorBox1Change(Sender: TObject);

begin

  p.Color := ColorBox1.Selected;

  Repaint;

end;



procedure TForm1.ColorBox2Change(Sender: TObject);

begin

  b.Color := ColorBox2.Selected;

  Repaint;

end;



procedure TForm1.ComboBox1Change(Sender: TObject);

begin

  b.Color := ColorBox2.Selected;

  case ComboBox1.ItemIndex of

    0: b.Style := bsSolid;

    1: b.Style := bsClear;

    2: b.Style := bsHorizontal;

    3: b.Style := bsVertical;

    4: b.Style := bsFDiagonal;

    5: b.Style := bsBDiagonal;

    6: b.Style := bsCross;

    7: b.Style := bsDiagCross;  

  end;

  Repaint;

end;



procedure TForm1.FormDestroy(Sender: TObject);

begin

  p.Free;

  b.Free;

  DeleteEnhMetaFile(HMetaFile);

end;



end.


 
   

窗体文件:

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object Form1: TForm1

  Left = 0

  Top = 0

  Caption = 'Form1'

  ClientHeight = 197

  ClientWidth = 324

  Color = clBtnFace

  Font.Charset = DEFAULT_CHARSET

  Font.Color = clWindowText

  Font.Height = -11

  Font.Name = 'Tahoma'

  Font.Style = []

  OldCreateOrder = False

  Position = poDesktopCenter

  OnCreate = FormCreate

  OnDestroy = FormDestroy

  OnPaint = FormPaint

  PixelsPerInch = 96

  TextHeight = 13

  object ColorBox1: TColorBox

    Left = 200

    Top = 16

    Width = 116

    Height = 22

    ItemHeight = 16

    TabOrder = 0

    OnChange = ColorBox1Change

  end

  object ColorBox2: TColorBox

    Left = 200

    Top = 44

    Width = 116

    Height = 22

    ItemHeight = 16

    TabOrder = 1

    OnChange = ColorBox2Change

  end

  object ComboBox1: TComboBox

    Left = 200

    Top = 72

    Width = 116

    Height = 21

    ItemHeight = 13

    TabOrder = 2

    Text = 'ComboBox1'

    OnChange = ComboBox1Change

  end

end